.alpha.-Methylene-.gamma.-butyrolactone is useful as a monomer in the preparation of both homopolymers and copolymers.
An early synthesis of .alpha.-methylene-.gamma.-butyrolactone involved two steps (Watts et al., J. Chem. Soc. Chem. Comm. 27 (1970)). The first is carboxylation of .gamma.-butyrolactone with methyl methoxymagnesium carbonate (Stiles' reagent) to produce the acid. Next, the acid is briefly treated with a mixture of aqueous formaldehyde and diethylamine, followed by a separate treatment of the crude product with sodium acetate in acetic acid. The first step requires 6-7 hours and affords almost quantitative yields, whereas the second step can be accomplished in less than 30 minutes but with yields of only 50%.
A. W. Murray et al. Synthesis, January 1985, p 35-38 report the development of a two-step route to .alpha.-methylene-.gamma.-butyrolactone that consists of the reaction of .gamma.-butyrolactone with ethyl formate in the presence of sodium hydride base followed by the isolation of the resulting formyl derivative as its sodium salt and subsequent reaction with an aldehyde. B. S. Orlek et al., U.S. Pat. No. 5,166,357, use this same route specifying the use of formaldehyde as the aldehyde.
Although the above methods for the production of .alpha.-methylene lactones are useful, they are time consuming and are multipart processes. The instant invention represents an advance in the art as it is a single step process that produces the desired product in high yields and good selectivity.